Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/10—Organic non-cellulose fibres
  • D21H13/12—Organic non-cellulose fibres from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
  • C08L1/02—Cellulose; Modified cellulose
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
  • C08L1/08—Cellulose derivatives
  • C08L1/10—Esters of organic acids, i.e. acylates
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
  • C08L77/02—Polyamides derived from omega-amino carboxylic acids or from lactams thereof
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H1/00—Paper; Cardboard
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/10—Organic non-cellulose fibres
  • D21H13/20—Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H13/24—Polyesters
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/10—Organic non-cellulose fibres
  • D21H13/20—Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H13/26—Polyamides; Polyimides
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/53—Polyethers; Polyesters
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/002—Tissue paper; Absorbent paper
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H5/00—Special paper or cardboard not otherwise provided for
  • D21H5/12—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials
  • D21H5/20—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of organic non-cellulosic fibres too short for spinning, with or without cellulose fibres
  • D21H5/207—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of organic non-cellulosic fibres too short for spinning, with or without cellulose fibres polyester fibres
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/249921—Web or sheet containing structurally defined element or component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber
  • Y10T428/298—Physical dimension
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
  • Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
  • Y10T442/608—Including strand or fiber material which is of specific structural definition
  • Y10T442/614—Strand or fiber material specified as having microdimensions [i.e., microfiber]
  • Y10T442/626—Microfiber is synthetic polymer

Definitions

• the present invention pertains to water-dispersible fibers and fibrous articles comprising a sulfopolyester.
• the invention further pertains to multicomponent fibers comprising a sulfopolyester, microdenier fibers, including short-cut microfibers, and fibrous articles prepared therefrom.
• the invention also pertains to processes to produce water-dispersible, multicomponent, and microdenier fibers and to nonwoven fabrics prepared therefrom.
• the fibers and fibrous articles have applications in flushable personal care products and medical products.
• Fibers, melt blown webs and other melt spun fibrous articles have been made from thermoplastic polymers, such as poly(propylene), polyamides, and polyesters.
• thermoplastic polymers such as poly(propylene), polyamides, and polyesters.
• One common application of these fibers and fibrous articles are nonwoven fabrics and, in particular, in personal care products such as wipes, feminine hygiene products, baby diapers, adult incontinence briefs, hospital/surgical and other medical disposables, protective fabrics and layers, geotextiles, industrial wipes, and filter media.
• personal care products made from conventional thermoplastic polymers are difficult to dispose of and are usually placed in landfills.
• One promising alternative method of disposal is to make these products or their components "flushable", i.e., compatible with public sewerage systems.
• thermoplastic polymers now used in personal care products are not inherently water-dispersible or soluble and, hence, do not produce articles that readily disintegrate and can be disposed of in a sewerage system or recycled easily.
• typical nonwoven technology is based on the multidirectional deposition of fibers that are treated with a resin binding adhesive to form a web having strong integrity and other desirable properties.
• the resulting assemblies generally have poor water-responsivity and are not suitable for flushable applications.
• the presence of binder also may result in undesirable properties in the final product, such as reduced sheet wettability, increased stiffness, stickiness, and higher production costs. It is also difficult to produce a binder that will exhibit adequate wet strength during use and yet disperse quickly upon disposal.
• nonwoven assemblies using these binders may either disintegrate slowly under ambient conditions or have less than adequate wet strength properties in the presence of body fluids.
• pH and ion-sensitive water-dispersible binders such as lattices containing acrylic or methacrylic acid with or without added salts, are known and described, for example, in U.S. Patent No. 6,548,592 Bl.
• Ion concentrations and pH levels in public sewerage and residential septic systems can vary widely among geographical locations and may not be sufficient for the binder to become soluble and disperse. In this case, the fibrous articles will not disintegrate after disposal and can clog drains or sewer laterals.
• Multicomponent fibers containing a water-dispersible component and a thermoplastic water non-dispersible component have been described, for example, in U.S. Patent No.'s 5,916,678; 5,405,698; 4,966,808; 5,525282; 5,366,804; 5,486,418.
• these multicomponent fibers may be a bicomponent fiber having a shaped or engineered transverse cross section such as, for example, an islands-in-the-sea, sheath core, side-by-side, or segmented pie configuration.
• Such oil finishes, pigments, and fillers require additional processing steps and can impart undesirable properties to the final fiber.
• Many water-dispersible polymers also require alkaline solutions for their removal which can cause degradation of the other polymer components of the fiber such as, for example, reduction of inherent viscosity, tenacity, and melt strength. Further, some water-dispersible polymers can not withstand exposure to water during hydroentanglement and, thus, are not suitable for the manufacture of nonwoven webs and fabrics.
• the water-dispersible component may serve as a bonding agent for the thermoplastic fibers in nonwoven webs. Upon exposure to water, the fiber to fiber bonds come apart such that the nonwoven web loses its integrity and breaks down into individual fibers.
• the thermoplastic fiber components of these nonwoven webs are not water-dispersible and remain present in the aqueous medium and, thus, must eventually be removed from municipal wastewater treatment plants. Hydroentanglement may be used to produce disintegratable nonwoven fabrics without or with very low levels ( ⁇ 5 wt%) of added binder to hold the fibers together. Although these fabrics may disintegrate upon disposal, they often utilize fibers that are not water soluble or water-dispersible and may result in entanglement and plugging within sewer systems. Any added water-dispersible binders also must be minimally affected by hydroentangling and not form gelatinous buildup or cross-link, and thereby contribute to fabric handling or sewer related problems.
• a few water-soluble or water-dispersible polymers are available, but are generally not applicable to melt blown fiber forming operations or melt spinning in general.
• Polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyacrylic acid are not melt processable as a result of thermal decomposition that occurs at temperatures below the point where a suitable melt viscosity is attained.
• High molecular weight polyethylene oxide may have suitable thermal stability, but would provide a high viscosity solution at the polymer interface resulting in a slow rate of disintegration.
• Water-dispersible sulfopolyesters have been described, for example, in U.S.
• a water-dispersible fiber and fibrous articles prepared therefrom that exhibit adequate tensile strength, absorptivity, flexibility, and fabric integrity in the presence of moisture, especially upon exposure to human bodily fluids.
• a fibrous article is needed that does not require a binder and completely disperses or dissolves in residential or municipal sewerage systems.
• melt blown webs spunbond fabrics, hydroentangled fabrics, wet-laid nonwovens, dry-laid non-wovens, bicomponent fiber components, adhesive promoting layers, binders for cellulosics, flushable nonwovens and films, dissolvable binder fibers, protective layers, and carriers for active ingredients to be released or dissolved in water.
• multicomponent fiber having a water-dispersible component that does not exhibit excessive blocking or fusing of filaments during spinning operations, is easily removed by hot water at neutral or slightly acidic pH, and is suitable for hydroentangling processes to manufacture nonwoven fabrics.
• These multicomponent fibers can be utilized to produce microfibers that can be used to produce various articles. Other extrudable and melt spun fibrous materials are also possible.
• a water-dispersible fiber comprising:
• the fiber contains less than 10 weight percent of a pigment or filler, based on the total weight of the fiber.
• n is an integer in the range of 2 to about 500;
• (C) optionally, a water non-dispersible polymer blended with the sulfopolyester to form a blend with the proviso that the blend is an immiscible blend;
• the fiber contains less than 10 weight percent of a pigment or filler, based on the total weight of the fiber.
• the water-dispersible, fibrous articles of the present invention include personal care articles such as, for example, wipes, gauze, tissue, diapers, training pants, sanitary napkins, bandages, wound care, and surgical dressings.
• personal care articles such as, for example, wipes, gauze, tissue, diapers, training pants, sanitary napkins, bandages, wound care, and surgical dressings.
• the fibrous articles of our invention are flushable, that is, compatible with and suitable for disposal in residential and municipal sewerage systems.
• n is an integer in the range of 2 to about 500;
• the fiber contains less than 10 weight percent of a pigment or filler, based on the total weight of the fiber.
• the sulfopolyester has a glass transition temperature of at least 57°C which greatly reduces blocking and fusion of the fiber during winding and long term storage.
• the sulfopolyester may be removed by contacting the multicomponent fiber with water to leave behind the water non-dispersible segments as microdenier fibers.
• Our invention therefore, also provides a process for microdenier fibers comprising:
• A spinning a water dispersible sulfopolyester having a glass transition temperature (Tg) of at least 57°C and one or more water non-dispersible polymers immiscible with the sulfopolyester into multicomponent fibers, the sulfopolyester comprising:
• the fibers have a plurality of segments comprising the water non- dispersible polymers wherein the segments are substantially isolated from each other by the sulfopolyester intervening between the segments and the fibers contain less than 10 weight percent of a pigment or filler, based on the total weight of the fibers;
• n is an integer in the range of 2 to about 500; and (iv) 0 to about 20 mole , based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein the functional groups are hydroxyl, carboxyl, or a combination thereof.
• n is an integer in the range of 2 to about 500;
• the fiber has an as-spun denier of less than about 6 denier per filament;
• the water dispersible sulfopolyesters exhibits a melt viscosity of less than about 12,000 poise measured at 240°C at a strain rate of 1 rad/sec, and wherein the sulfopolyester comprises less than about 25 mole % of residues of at least one sulfomonomer, based on the total moles of diacid or diol residues.
• a multicomponent extrudate having a shaped cross section comprising:
• a process for making a multicomponent fiber having a shaped cross section comprising extruding at least one water dispersible sulfopolyester and one or more water non-dispersible polymers immiscible with the sulfopolyester to produce a multicomponent extrudate, wherein the multicomponent extrudate has a plurality of domains comprising said water non-dispersible polymers and said domains are substantially isolated from each other by said sulfopolyester intervening between said domains; and melt drawing the multicomponent extrudate at a speed of at least about 2000 m/min to produce the multicomponent fiber.
• the present invention provides a process for producing microdenier fibers comprising:
• a process for making a microdenier fiber web comprising:
• Step (B) collecting the multicomponent fibers of Step (A) to form a non-woven web
• sulfopolyester comprises:
• Multicomponent fibers processes for producing multicomponent fibers, microfibers produced from multicomponent fibers, process for producing microfibers from multicomponent fibers and articles produced from microfibers are disclosed in the following U.S. Patents and Patent Applications: U.S. Patent No. 6,989,193; U.S. Patent No. 7,902,094; U.S. Patent No. 7,892,993; U.S. Patent No. 7,687,143; US Patent Application Serial Number 12/199,304 filed on August 27 th , 2008, U.S. Patent Application Serial Number 12/909,574 filed on November 21 st , 2010, U.S. Patent Application No. 13/352,362 filed on January 18 th , 2012, U.S. Patent Application Nos.
• FIGS 1-5 illustrate the characteristics of hand sheets produced in Examples 41-42. DETAILED DESCRIPTION
• n is an integer in the range of 2 to about 500; and (iv) 0 to about 25 mole , based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein the functional groups are hydroxyl, carboxyl, or a combination thereof.
• Our fiber may optionally include a water- dispersible polymer blended with the sulfopolyester and, optionally, a water non-dispersible polymer blended with the sulfopolyester with the proviso that the blend is an immiscible blend.
• Our fiber contains less than 10 weight percent of a pigment or filler, based on the total weight of the fiber.
• the present invention also includes fibrous articles comprising these fibers and may include personal care products such as wipes, gauze, tissue, diapers, adult incontinence briefs, training pants, sanitary napkins, bandages, and surgical dressings.
• the fibrous articles may have one or more absorbent layers of fibers.
• These fibers of the water non-dispersible polymer have fiber size much smaller than the multi- component fiber before removing the sulfopolyester.
• the sulfopolyester and water non-dispersible polymers may be fed to a polymer distribution system where the polymers are introduced into a segmented spinneret plate.
• the polymers follow separate paths to the fiber spinneret and are combined at the spinneret hole which comprises either two concentric circular holes thus providing a sheath-core type fiber, or a circular spinneret hole divided along a diameter into multiple parts to provide a fiber having a side-by-side type.
• the unicomponent fibers and fibrous articles produced from the unicomponent fibers of the present invention are water-dispersible and, typically, completely disperse at room temperature. Higher water temperatures can be used to accelerate their dispersibility or rate of removal from the nonwoven or multicomponent fiber.
• dissipate means that, using a sufficient amount of deionized water (e.g., 100: 1 watenfiber by weight) to form a loose suspension or slurry of the fibers or fibrous article, at a temperature of about 60°C, and within a time period of up to 5 days, the fiber or fibrous article dissolves, disintegrates, or separates into a plurality of incoherent pieces or particles distributed more or less throughout the medium such that no recognizable filaments are recoverable from the medium upon removal of the water, for example, by filtration or evaporation.
• a sufficient amount of deionized water e.g., 100: 1 watenfiber by weight
• water-dispersible as used herein in reference to the sulfopolyester as one component of a multicomponent fiber or fibrous article, also is intended to be synonymous with the terms “water-dissipatable”, “water- disintegratable”, “water-dissolvable”, “water-dispellable”, “water soluble”, “water-removable”, “hydrosoluble”, and “hydrodispersible” and is intended to mean that the sulfopolyester component is sufficiently removed from the multicomponent fiber and is dispersed or dissolved by the action of water to enable the release and separation of the water non-dispersible fibers contained therein.
• a sulfopolyester containing 30 mole of a sulfomonomer which may be a dicarboxylic acid, a diol, or hydroxycarboxylic acid, based on the total repeating units, means that the sulfopolyester contains 30 mole sulfomonomer out of a total of 100 mole repeating units.
• a sulfopolyester containing 30 mole of a dicarboxylic acid sulfomonomer, based on the total acid residues means the sulfopolyester contains 30 mole sulfomonomer out of a total of 100 mole acid residues.
• the sulfopolyesters described herein have an inherent viscosity, abbreviated hereinafter as "Hi.V.”, of at least about 0.1 dL/g, preferably about 0.2 to 0.3 dL/g, and most preferably greater than about 0.3 dL/g, measured in a 60/40 parts by weight solution of phenol/tetrachloroethane solvent at 25°C and at a concentration of about 0.5 g of sulfopolyester in 100 mL of solvent.
• Hi.V inherent viscosity
• polystyrene resin encompasses both “homopolyesters” and “copolyesters” and means a synthetic polymer prepared by the polycondensation of difunctional carboxylic acids with difunctional hydroxyl compound.
• sulfopolyester means any polyester comprising a sulfomonomer.
• the difunctional carboxylic acid is a dicarboxylic acid and the difunctional hydroxyl compound is a dihydric alcohol such as, for example glycols and diols.
• the difunctional carboxylic acid may be a hydroxy carboxylic acid such as, for example, p- hydroxybenzoic acid
• the difunctional hydroxyl compound may be a aromatic nucleus bearing 2 hydroxy substituents such as, for example, hydroquinone.
• the term "residue”, as used herein, means any organic structure incorporated into the polymer through a polycondensation reaction involving the corresponding monomer.
• the dicarboxylic acid residue may be derived from a dicarboxylic acid monomer or its associated acid halides, esters, salts, anhydrides, or mixtures thereof.
• dicarboxylic acid is intended to include dicarboxylic acids and any derivative of a dicarboxylic acid, including its associated acid halides, esters, half-esters, salts, half-salts, anhydrides, mixed anhydrides, or mixtures thereof, useful in a polycondensation process with a diol to make a high molecular weight polyester.
• the sulfopolyester of the present invention includes one or more dicarboxylic acid residues.
• the dicarboxylic acid residue may comprise from about 60 to about 100 mole of the acid residues.
• concentration ranges of dicarboxylic acid residues are from about 60 mole to about 95 mole , and about 70 mole to about 95 mole .
• dicarboxylic acids that may be used include aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, aromatic dicarboxylic acids, or mixtures of two or more of these acids.
• suitable dicarboxylic acids include, but are not limited to, succinic; glutaric; adipic; azelaic; sebacic; fumaric; maleic; itaconic; 1,3-cyclohexanedicarboxylic; 1,4-cyclohexanedicarboxylic; diglycolic; 2,5-norbornanedicarboxylic; phthalic; terephthalic; 1,4-naphthalenedicarboxylic; 2,5-naphthalenedicarboxylic; diphenic; 4,4'-oxydibenzoic; 4,4'-sulfonyidibenzoic; and isophthalic.
• the preferred dicarboxylic acid residues are isophthalic, terephthalic, and 1,4- cyclohexanedicarboxylic acids, or if diesters are used, dimethyl terephthalate, dimethyl isophthalate, and dimethyl- 1,4-cyclohexanedicarboxylate with the residues of isophthalic and terephthalic acid being especially preferred.
• dicarboxylic acid methyl ester is the most preferred embodiment, it is also acceptable to include higher order alkyl esters, such as ethyl, propyl, isopropyl, butyl, and so forth.
• aromatic esters, particularly phenyl also may be employed.
• the sulfopolyester includes about 4 to about 40 mole , based on the total repeating units, of residues of at least one sulfomonomer having 2 functional groups and one or more sulfonate groups attached to an aromatic or cycloaliphatic ring wherein the functional groups are hydroxyl, carboxyl, or a combination thereof. Additional examples of concentration ranges for the sulfomonomer residues are about 4 to about 35 mole , about 8 to about 30 mole , and about 8 to about 25 mole , based on the total repeating units.
• the sulfomonomer may be a dicarboxylic acid or ester thereof containing a sulfonate group, a diol containing a sulfonate group, or a hydroxy acid containing a sulfonate group.
• sulfonate refers to a salt of a sulfonic acid having the structure "-SO 3 M" wherein M is the cation of the sulfonate salt.
• the cation of the sulfonate salt may be a metal ion such as Li + , Na + , K + , Mg ++ , Ca ++ , Ni ++ , Fe ++ , and the like.
• the cation of the sulfonate salt may be non-metallic such as a nitrogenous base as described, for example, in U.S. Patent No. 4,304,901.
• Nitrogen-based cations are derived from nitrogen- containing bases, which may be aliphatic, cycloaliphatic, or aromatic compounds. Examples of such nitrogen containing bases include ammonia, dimethylethanolamine, diethanolamine, triethanolamine, pyridine, morpholine, and piperidine.
• the method of this invention for preparing sulfopolyesters containing nitrogen-based sulfonate salt groups is to disperse, dissipate, or dissolve the polymer containing the required amount of sulfonate group in the form of its alkali metal salt in water and then exchange the alkali metal cation for a nitrogen-based cation.
• the resulting sulfopolyester is completely dispersible in water with the rate of dispersion dependent on the content of sulfomonomer in the polymer, temperature of the water, surface area/thickness of the sulfopolyester, and so forth.
• a divalent metal ion is used, the resulting sulfopolyesters are not readily dispersed by cold water but are more easily dispersed by hot water. Utilization of more than one counterion within a single polymer composition is possible and may offer a means to tailor or fine-tune the water- responsivity of the resulting article of manufacture.
• sulfomonomers residues include monomer residues where the sulfonate salt group is attached to an aromatic acid nucleus, such as, for example, benzene; naphthalene; diphenyl; oxydiphenyl; sulfonyldiphenyl; and methylenediphenyl or cycloaliphatic rings, such as, for example, cyclohexyl; cyclopentyl; cyclobutyl; cycloheptyl; and cyclooctyl.
• aromatic acid nucleus such as, for example, benzene; naphthalene; diphenyl; oxydiphenyl; sulfonyldiphenyl; and methylenediphenyl or cycloaliphatic rings, such as, for example, cyclohexyl; cyclopentyl; cyclobutyl; cycloheptyl; and cyclooctyl.
• polyester using, for example, a sodium sulfonate salt, and ion-exchange methods to replace the sodium with a different ion, such as zinc, when the polymer is in the dispersed form.
• a sodium sulfonate salt and ion-exchange methods to replace the sodium with a different ion, such as zinc, when the polymer is in the dispersed form.
• This type of ion exchange procedure is generally superior to preparing the polymer with divalent salts insofar as the sodium salts are usually more soluble in the polymer reactant melt-phase.
• the sulfopolyester includes one or more diol residues which may include aliphatic, cycloaliphatic, and aralkyl glycols.
• the cycloaliphatic diols for example, 1,3- and 1,4-cyclohexanedimethanol, may be present as their pure cis or trans isomers or as a mixture of cis and trans isomers.
• diol is synonymous with the term "glycol” and means any dihydric alcohol.
• the molecular weight may range from greater than 300 to about 22,000 g/mol.
• the molecular weight and the mole are inversely proportional to each other; specifically, as the molecular weight is increased, the mole % will be decreased in order to achieve a designated degree of hydrophilicity.
• a PEG having a molecular weight of 1000 may constitute up to 10 mole of the total diol, while a PEG having a molecular weight of 10,000 would typically be incorporated at a level of less than 1 mole of the total diol.
• dimer, trimer, and tetramer diols may be formed in situ due to side reactions that may be controlled by varying the process conditions.
• varying amounts of diethylene, triethylene, and tetraethylene glycols may be formed from ethylene glycol from an acid-catalyzed dehydration reaction which occurs readily when the polycondensation reaction is carried out under acidic conditions.
• the presence of buffer solutions may be added to the reaction mixture to retard these side reactions. Additional compositional latitude is possible, however, if the buffer is omitted and the dimerization, trimerization, and tetramerization reactions are allowed to proceed.
• the sulfopolyester of the present invention may include from 0 to about 25 mole , based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein the functional groups are hydroxyl, carboxyl, or a combination thereof.
• branching monomers are 1,1,1-trimethylol propane, 1,1,1-trimethylolethane, glycerin, pentaerythritol, erythritol, threitol, dipentaerythritol, sorbitol, trimellitic anhydride, pyromellitic dianhydride, dimethylol propionic acid, or combinations thereof.
• typical glass transition temperatures of the dry sulfopolyesters our invention are about 30°C, about 48°C, about 55°C, about 65°C, about 70°C, about 75°C, about 85°C, and about 90°C.
• miscible is intended to mean that the blend has a single, homogeneous amorphous phase as indicated by a single composition-dependent Tg.
• a first polymer that is miscible with second polymer may be used to "plasticize” the second polymer as illustrated, for example, in U.S. Patent No. 6,211,309.
• the term “immiscible”, as used herein denotes a blend that shows at least 2, randomly mixed, phases and exhibits more than one Tg. Some polymers may be immiscible and yet compatible with the sulfopolyester.
• Our invention also provides a water-dispersible fiber comprising a sulfopolyester having a glass transition temperature (Tg) of at least 25°C, wherein the sulfopolyester comprises:
• the sulfopolyester should have a glass transition temperature (Tg) of at least 25°C, but may have, for example, a Tg of about 35°C, about 48°C, about 55°C, about 65°C, about 70°C, about 75°C, about 85°C, and about 90°C.
• Tg glass transition temperature
• the sulfopolyester may contain other concentrations of isophthalic acid residues, for example, about 60 to about 95 mole , and about 75 to about 95 mole . Further examples of isophthalic acid residue concentrations ranges are about 70 to about 85 mole , about 85 to about 95 mole and about 90 to about 95 mole .
• the sulfopolyesters of the instant invention are readily prepared from the appropriate dicarboxylic acids, esters, anhydrides, or salts, sulfomonomer, and the appropriate diol or diol mixtures using typical polycondensation reaction conditions. They may be made by continuous, semi-continuous, and batch modes of operation and may utilize a variety of reactor types. Examples of suitable reactor types include, but are not limited to, stirred tank, continuous stirred tank, slurry, tubular, wiped- film, falling film, or extrusion reactors.
• continuous as used herein means a process wherein reactants are introduced and products withdrawn simultaneously in an uninterrupted manner.
• continuous it is meant that the process is substantially or completely continuous in operation and is to be contrasted with a “batch” process.
• Continuous is not meant in any way to prohibit normal interruptions in the continuity of the process due to, for example, start-up, reactor maintenance, or scheduled shut down periods.
• batch process as used herein means a process wherein all the reactants are added to the reactor and then processed according to a predetermined course of reaction during which no material is fed or removed into the reactor.
• continuous means a process where some of the reactants are charged at the beginning of the process and the remaining reactants are fed continuously as the reaction progresses.
• the polycondensation step may be conducted under reduced pressure which ranges from about 53 kPa (400 torr) to about 0.013 kPa (0.1 torr). Stirring or appropriate conditions are used in both stages to ensure adequate heat transfer and surface renewal of the reaction mixture.
• the reactions of both stages are facilitated by appropriate catalysts such as, for example, alkoxy titanium compounds, alkali metal hydroxides and alcoholates, salts of organic carboxylic acids, alkyl tin compounds, metal oxides, and the like.
• a three-stage manufacturing procedure similar to that described in U.S. Patent No. 5,290,631, may also be used, particularly when a mixed monomer feed of acids and esters is employed.
• the fiber has an islands-in-the-sea or segmented pie cross section and contains less than 10 weight percent of a pigment or filler, based on the total weight of the fiber.
• Non-aromatic is intended to include both aliphatic and cycloaliphatic structures such as, for example, diols and dicarboxylic acids, which contain as a backbone a straight or branched chain or cyclic arrangement of the constituent carbon atoms which may be saturated or paraffinic in nature, unsaturated, i.e., containing non-aromatic carbon-carbon double bonds, or acetylenic, i.e., containing carbon-carbon triple bonds.
• diols and dicarboxylic acids which contain as a backbone a straight or branched chain or cyclic arrangement of the constituent carbon atoms which may be saturated or paraffinic in nature, unsaturated, i.e., containing non-aromatic carbon-carbon double bonds, or acetylenic, i.e., containing carbon-carbon triple bonds.
• non- aromatic is intended to include linear and branched, chain structures (referred to herein as “aliphatic”) and cyclic structures (referred to herein as “alicyclic” or “cycloaliphatic”).
• aliphatic linear and branched, chain structures
• cyclic referred to herein as "alicyclic” or “cycloaliphatic”
• non-aromatic is not intended to exclude any aromatic substituents which may be attached to the backbone of an aliphatic or cycloaliphatic diol or dicarboxylic acid.
• the difunctional carboxylic acid typically is a aliphatic dicarboxylic acid such as, for example, adipic acid, or an aromatic dicarboxylic acid such as, for example, terephthalic acid.
• diols which may be used include, but are not limited to, ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 2,2- dimethyl-l,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- hexanediol, polyethylene glycol, diethylene glycol, 2,2,4-trimethyl-l,6- hexanediol, thiodiethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-l,3-cyclobutanediol, triethylene glycol, and tetraethylene glycol with the preferred diols comprising one or more diols selected from 1,4-butanediol; 1,3-propanediol; ethylene glycol; 1,
• Non-limiting examples of non-aromatic diacids include malonic, succinic, glutaric, adipic, pimelic, azelaic, sebacic, fumaric, 2,2-dimethyl glutaric, suberic, 1,3- cyclopentanedicarboxylic, 1,4-cyclohexanedicarboxylic, 1,3- cyclohexanedicarboxylic, diglycolic, itaconic, maleic, and 2,5-norbornane- dicarboxylic.
• the A APE comprises about 1 to about 65 mole%, based on the total moles of diacid residues, of the residues of one or more substituted or unsubstituted aromatic dicarboxylic acids containing 6 to about 10 carbon atoms.
• substituted aromatic dicarboxylic acids they will typically contain 1 to about 4 substituents selected from halo, C6-C 10 aryl, and CrC 4 alkoxy.
• the AAPE may contain the residues of a branching agent.
• the mole percentage ranges for the branching agent are from about 0 to about 2 mole , preferably about 0.1 to about 1 mole , and most preferably about 0.1 to about 0.5 mole based on the total moles of diacid or diol residues (depending on whether the branching agent contains carboxyl or hydroxyl groups).
• the branching agent preferably has a weight average molecular weight of about 50 to about 5000, more preferably about 92 to about 3000, and a functionality of about 3 to about 6.
• Each segment of the water non-dispersible polymer may be different from others in fineness and may be arranged in any shaped or engineered cross- sectional geometry known to persons skilled in the art.
• the sulfopolyester and a water non-dispersible polymer may be used to prepare a bicomponent fiber having an engineered geometry such as, for example, a side- by-side, "islands-in-the-sea", segmented pie, other splitables, sheath/core, or other configurations known to persons skilled in the art.
• Other multicomponent configurations are also possible. Subsequent removal of a side, the "sea", or a portion of the "pie” can result in very fine fibers.
• the process of preparing bicomponent fibers also is well known to persons skilled in the art.
• the sulfopolyester fibers of this invention may be present in amounts of about 10 to about 90 weight and will generally be used in the sheath portion of sheath/core fibers.
• the resulting bicomponent or multicomponent fiber is not completely water-dispersible.
• Side by side combinations with significant differences in thermal shrinkage can be utilized for the development of a spiral crimp. If crimping is desired, a saw tooth or stuffer box crimp is generally suitable for many applications.
• the second polymer component is in the core of a sheath/core configuration, such a core optionally may be stabilized.
• the sulfopolyesters are particularly useful for fibers having an "islands- in-the-sea” or “segmented pie” cross section as they only requires neutral or slightly acidic (i.e., "soft” water) to disperse, as compared to the caustic- containing solutions that are sometimes required to remove other water dispersible polymers from multicomponent fibers.
• soft water as used in this disclosure means that the water has up to 5 grains per gallon as CaC0 3 (1 grain of CaC0 3 per gallon is equivalent to 17.1 ppm).
• a multicomponent fiber comprising:
• n is an integer in the range of 2 to about 500;
• the fiber has an islands-in-the-sea or segmented pie cross section and contains less than 10 weight percent of a pigment or filler, based on the total weight of the fiber.
• the dicarboxylic acids, diols, sulfopolyester, sulfomonomers, branching monomers residues, and water non-dispersible polymers are as described previously.
• sulfopolyester have a Tg of at least 57°C.
• the sulfopolyester may be a single sulfopolyester or a blend of one or more sulfopolyester polymers.
• glass transition temperatures that may be exhibited by the sulfopolyester or sulfopolyester blends are at least 65°C, at least 70°C, at least 75°C, at least 85°C, and at least 90°C.
• the sulfopolyester may comprise about 75 to about 96 mole of one or more residues of isophthalic acid or terephthalic acid and about 25 to about 95 mole of a residue of diethylene glycol.
• examples of the water non-dispersible polymers are polyolefins, polyesters, polyamides, polylactides, polycaprolactones, polycarbonates, polyurethanes, cellulose esters, and polyvinyl chlorides.
• the water non-dispersible polymer may be biodegradable or biodisintegratable.
• the water non-dispersible polymer may be an aliphatic-aromatic polyester as described previously.
• Our novel multicomponent fiber may be prepared by any number of methods known to persons skilled in the art.
• the present invention thus provides a process for a multicomponent fiber having a shaped cross section comprising: spinning a water dispersible sulfopolyester having a glass transition temperature (Tg) of at least 57°C and one or more water non-dispersible polymers immiscible with the sulfopolyester into a fiber, the sulfopolyester comprising:
• n is an integer in the range of 2 to about 500;
• the fiber has a plurality of segments comprising the water non- dispersible polymers and the segments are substantially isolated from each other by the sulfopolyester intervening between the segments and the fiber contains less than 10 weight percent of a pigment or filler, based on the total weight of the fiber.
• the multicomponent fiber may be prepared by melting the sulfopolyester and one or more water non-dispersible polymers in separate extruders and directing the individual polymer flows into one spinneret or extrusion die with a plurality of distribution flow paths such that the water non-dispersible polymer component form small segments or thin strands which are substantially isolated from each other by the intervening sulfopolyester.
• the cross section of such a fiber may be, for example, a segmented pie arrangement or an islands-in-the-sea arrangement.
• the sulfopolyester and one or more water non-dispersible polymers are separately fed to the spinneret orifices and then extruded in sheath-core form in which the water non-dispersible polymer forms a "core" that is substantially enclosed by the sulfopolyester "sheath" polymer.
• the orifice supplying the "core" polymer is in the center of the spinning orifice outlet and flow conditions of core polymer fluid are strictly controlled to maintain the concentricity of both components when spinning.
• a multicomponent fiber having a side-by-side cross section or configuration may be produced by coextruding the water dispersible sulfopolyester and water non-dispersible polymer through orifices separately and converging the separate polymer streams at substantially the same speed to merge side-by-side as a combined stream below the face of the spinneret; or (2) by feeding the two polymer streams separately through orifices, which converge at the surface of the spinneret, at substantially the same speed to merge side -by-side as a combined stream at the surface of the spinneret.
• the velocity of each polymer stream, at the point of merge, is determined by its metering pump speed, the number of orifices, and the size of the orifice.
• the dicarboxylic acids, diols, sulfopolyester, sulfomonomers, branching monomers residues, and water non-dispersible polymers are as described previously.
• the sulfopolyester has a glass transition temperature of at least 57°C. Further examples of glass transition temperatures that may be exhibited by the sulfopolyester or sulfopolyester blend are at least 65°C, at least 70°C, at least 75°C, at least 85°C, and at least 90°C.
• the sulfopolyester may comprise about 50 to about 96 mole of one or more residues of isophthalic acid or terephthalic acid, based on the total acid residues; and about 4 to about 30 mole , based on the total acid residues, of a residue of sodiosulfoisophthalic acid; and 0 to about 20 mole , based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein the functional groups are hydroxyl, carboxyl, or a combination thereof.
• the sulfopolyester may comprise about 75 to about 96 mole of one or more residues of isophthalic acid or terephthalic acid and about 25 to about 95 mole of a residue of diethylene glycol.
• examples of the water non-dispersible polymers are polyolefins, polyesters, polyamides, polylactides, polycaprolactone, polycarbonate, polyurethane, and polyvinyl chloride.
• the water non-dispersible polymer may be biodegradable or biodisintegratable.
• the water non-dispersible polymer may be an aliphatic-aromatic polyester as described previously. Examples of shaped cross sections include, but are not limited to, islands-in-the-sea, side-by-side, sheath- core, or segmented pie configurations.
• a process for making a multicomponent fiber having a shaped cross section comprising: spinning at least one water dispersible sulfopolyester and one or more water non-dispersible polymers immiscible with the sulfopolyester to produce a multicomponent fiber, wherein the multicomponent fiber has a plurality of domains comprising the water non-dispersible polymers and the domains are substantially isolated from each other by the sulfopolyester intervening between the domains; wherein the water dispersible sulfopolyester exhibits a melt viscosity of less than about 12,000 poise measured at 240°C at a strain rate of 1 rad/sec, and wherein the sulfopolyester comprising less than about 25 mole % of residues of at least one sulfomonomer, based on the total moles of diacid or diol residues; and wherein the multicomponent fiber has an as- spun denier
• a process for making a multicomponent fiber having a shaped cross section comprising:
• (B) melt drawing the multicomponent extrudate at a speed of at least about 2000 m/min to produce the multicomponent fiber.
• the process includes the step of melt drawing the multicomponent extrudate at a speed of at least about 2000 m/min, more preferably, at least about 3000 m/min, and most preferably at least 4500 m/min.
• the fibers are quenched with a cross flow of air whereupon the fibers solidify.
• Various finishes and sizes may be applied to the fiber at this stage.
• the cooled fibers typically, are subsequently drawn and wound up on a take up spool.
• Other additives may be incorporated in the finish in effective amounts like emulsifiers, antistatics, antimicrobials, antifoams, lubricants, thermo stabilizers, UV stabilizers, and the like.
• the drawn fibers may be textured and wound-up to form a bulky continuous filament.
• This one-step technique is known in the art as spin- draw-texturing.
• Other embodiments include flat filament (non-textured) yarns, or cut staple fiber, either crimped or uncrimped.
• the sulfopolyester may be later removed by dissolving the interfacial layers or pie segments and leaving the smaller filaments or microdenier fibers of the water non-dispersible polymer(s).
• Our invention thus provides a process for microdenier fibers comprising:
• A spinning a water dispersible sulfopolyester having a glass transition temperature (Tg) of at least 57°C and one or more water non-dispersible polymers immiscible with the sulfopolyester into multicomponent fibers, the sulfopolyester comprising:
• n is an integer in the range of 2 to about 500;
• the fibers have a plurality of segments comprising the water non-dispersible polymers wherein the segments are substantially isolated from each other by the sulfopolyester intervening between the segments and the fibers contain less than 10 weight percent of a pigment or filler, based on the total weight of the fibers;
• the multicomponent fiber is contacted with water at a temperature of about 25°C to about 100°C, preferably about 50°C to about 80°C for a time period of from about 10 to about 600 seconds whereby the sulfopolyester is dissipated or dissolved.
• the remaining water non-dispersible polymer microfibers typically will have an average fineness of 1 d/f or less, typically, 0.5 d/f or less, or more typically, 0.1 d/f or less.
• Typical applications of these remaining water non-dispersible polymer microfibers include nonwoven fabrics, such as, for example, artificial leathers, suedes, wipes, and filter media.
• Filter media produce from these microfibers can be utilized to filter air or liquids.
• Filter media for liquids include, but are not limited to, water, bodily fluids, solvents, and hydrocarbons.
• the ionic nature of sulfopolyesters also results in advantageously poor "solubility" in saline media, such as body fluids. Such properties are desirable in personal care products and cleaning wipes that are flushable or otherwise disposed in sanitary sewage systems.
• Selected sulfopolyesters have also been utilized as dispersing agents in dye baths and soil redeposition preventative agents during laundry cycles.
• a process for making microdenier fibers comprising spinning at least one water dispersible sulfopolyester and one or more water non-dispersible polymers immiscible with the water dispersible sulfopolyester into multicomponent fibers, wherein the multicomponent fibers have a plurality of domains comprising the water non-dispersible polymers wherein the domains are substantially isolated from each other by the sulfopolyester intervening between the domains; wherein the fiber has an as- spun denier of less than about 6 denier per filament; wherein the water dispersible sulfopolyester exhibits a melt viscosity of less than about 12,000 poise measured at 240°C at a strain rate of 1 rad/sec, and wherein the sulfopolyester comprising less than about 25 mole % of residues of at least one sulfomonomer, based on the total moles of diacid or diol residue
• microdenier fibers comprising:
• melt drawing of the multicomponent extrudates at a speed of at least about 2000 m/min, more preferably at least about 3000 m/min, and most preferably at least 4500 m/min.
• the water used to remove the sulfopolyester from the multicomponent fibers be above room temperature, more preferably the water is at least about 45°C, even more preferably at least about 60°C, and most preferably at least about 80°C.
• another process is provided to produce water non-dispersible polymer microfibers.
• the process comprises: a) cutting a multicomponent fiber into cut multicomponent fibers;
• the multicomponent fiber can be cut into any length that can be utilized to produce nonwoven articles.
• the multicomponent fiber is cut into lengths ranging from about 1mm to about 50 mm.
• the multicomponent fiber can be cut into a mixture of different lengths.
• the fiber-containing feedstock can comprise any other type of fiber that is useful in the production of nonwoven articles.
• the fiber- containing feedstock further comprises at least one fiber selected from the group consisting of cellulosic fiber pulp, glass fiber, polyester fibers, nylon fibers, polyolefin fibers, rayon fibers and cellulose ester fibers.
• the fiber-containing feedstock is mixed with water to produce a fiber mix slurry.
• the water utilized can be soft water or deionized water.
• Soft water has been previously defined in this disclosure.
• at least one water softening agent may be used to facilitate the removal of the water-dispersible sulfopolyester from the multicomponent fiber. Any water softening agent known in the art can be utilized.
• the water softening agent is a chelating agent or calcium ion sequestrant.
• Applicable chelating agents or calcium ion sequestrants are compounds containing a plurality of carboxylic acid groups per molecule where the carboxylic groups in the molecular structure of the chelating agent are separated by 2 to 6 atoms.
• Tetrasodium ethylene diamine tetraacetic acid (EDTA) is an example of the most common chelating agent, containing four carboxylic acid moieties per molecular structure with a separation of 3 atoms between adjacent carboxylic acid groups.
• Poly acrylic acid, sodium salt is an example of a calcium sequestrant containing carboxylic acid groups separated by two atoms between carboxylic groups.
• Sodium salts of maleic acid or succinic acid are examples of the most basic chelating agent compounds.
• applicable chelating agents include compounds which have in common the presence of multiple carboxylic acid groups in the molecular structure where the carboxylic acid groups are separated by the required distance (2 to 6 atom units) which yield a favorable steric interaction with di- or multi- valent cations such as calcium which cause the chelating agent to preferentially bind to di- or multi valent cations.
• Such compounds include, but are not limited to, diethylenetriaminepentaacetic acid; diethylenetriamine- ⁇ , ⁇ , ⁇ ', ⁇ ', ⁇ "- pentaacetic acid; pentetic acid; N,N-bis(2-(bis-(carboxymethyl)amino)ethyl)- glycine; diethylenetriamine pentaacetic acid; [[(carboxymethyl)imino]bis(ethylenenitrilo)]-tetra-acetic acid; edetic acid; ethylenedinitrilotetraacetic acid; EDTA, free base; EDTA free acid; ethylenediamine-N,N,N',N'-tetraacetic acid; hampene; versene; N,N'-l,2-ethane diylbis-(N-(carboxymethyl)glycine); ethylenediamine tetra-acetic acid; N,N- bis(carboxymethyl)glycine; triglycollamic acid; tri
• the amount of water softening agent needed depends on the hardness of the water utilized in terms of Ca ++ and other multivalent ions.
• the fiber mix slurry is heated to produce a heated fiber mix slurry.
• the temperature is that which is sufficient to remove a portion of the sulfopolyester from the multicomponent fiber.
• the fiber mix slurry is heated to a temperature ranging from about 50 C to about lOO C. Other temperature ranges are from about 70 ° C to about lOO C, about 80 C to about 100 ° C, and about 90 ° C to about 100 ° C.
• the fiber mix slurry is mixed in a shearing zone.
• the amount of mixing is that which is sufficient to disperse and remove a portion of the water dispersible sulfopolyester from the multicomponent fiber and separate the water non-dispersible polymer microfibers.
• 90% of the sulfopolyester is removed.
• 95% of the sulfopolyester is removed, and in yet another embodiment, 98% or greater of the sulfopolyester is removed.
• the shearing zone can comprise any type of equipment that can provide shearing action necessary to disperse and remove a portion of the water dispersible sulfopolyester from the multicomponent fiber and separate the water non-dispersible polymer microfibers.
• examples of such equipment include, but is not limited to, pulpers and refiners.
• the water dispersible sulfopolyester in the multicomponent fiber after contact with water and heating disperse and separate from the water non- dispersible polymer fiber to produce a slurry mixture comprising a sulfopolyester dispersion and the water non-dispersible polymer microfibers.
• the water non-dispersible polymer microfibers can then be separated from the sulfopolyester dispersion by any means known in the art.
• the slurry mixture can be routed through separating equipment, such as for example, screens and filters.
• the water non-dispersible polymer microfibers may be washed once or numerous times to remove more of the water-dispersible sulfopolyester.
• the removal of the water-dispersible sulfopolyester can be determined by physical observation of the slurry mixture.
• the water utilized to rinse the water non-dispersible polymer microfibers is clear if the water-dispersible sulfopolyester has been mostly removed. If the water-dispersible sulfopolyester is still being removed, the water utilized to rinse the water non-dispersible polymer microfibers can be milky. Further, if water-dispersible sulfopolyester remains on the water non-dispersible polymer microfibers, the microfibers can be somewhat sticky to the touch.
• the water-dispersible sulfopolyester can be recovered from the sulfopolyester dispersion by any method known in the art.
• a short-cut , water non- dispersible polymer microfiber comprising at least one water non- dispersible polymer wherein the water non-dispersible polymer microfiber has an equivalent diameter of less than 5 microns and length of less than 25 millimeters.
• This short-cut water non-dispersible polymer microfiber is produced by the processes previously described to produce microfibers.
• the short-cut water non-dispersible polymer microfiber has an equivalent diameter of less than 3 microns and length of less than 25 millimeters.
• the short-cut water non-dispersible polymer microfiber has an equivalent diameter of less than 5 microns or less than 3 microns.
• the short-cut water non-dispersible polymer microfiber can have lengths of less than 12 millimeters; less than 10 millimeters, less than 6.5 millimeters, and less than 3.5 millimeters.
• the domains or segments in the multicomponent fiber once separated yield the water non-dispersible polymer microfibers.
• Aspect ratio is defined as the length of the short-cut, water non- dispersible polymer microfiber divided by the diameter. Selection of the aspect ratio of the short-cut, water non-dispersible polymer microfiber can affect the processing of the microfiber in nonwoven processes. When the proper aspect ratio is selected, dispersion of the short-cut water non-dispersible polymer microfiber in nonwoven processes can be improved by preventing clumps or knots of the short-cut water non-dispersible polymer microfiber with itself or with other components in the nonwoven process.
• the strength of nonwoven articles containing the shortcut water non-dispersible polymer microfibers can be improved since the length is adequate to allow the short-cut water non-dispersible polymer microfiber to entangle with itself and/or other fibers.
• the aspect ratio is sufficiently low such that the short-cut water non-dispersible polymer microfibers will not entangle with one another either when the sulfopolyester is being removed or during the nonwoven processes such that the short-cut water non-dispersible polymer microfibers aggregate together or with other components or other fibers to produce knots or clumps.
• the aspect ratio of the short-cut, water non-dispersible polymer microfiber is sufficiently high such that the short-cut water non-dispersible polymer microfiber can still entangle with each other and/or with other fibers in the nonwoven article to provide strength to the nonwoven article.
• the aspect ratio of the short-cut, water non-dispersible polymer microfiber has an aspect ratio (length/diameter) ranging from about 300 to about 1000. In other embodiments of the invention, the aspect ratio can range from about 300 to about 750, about 300 to about 650, about 300 to about 550, and about 300 to about 450. Other aspect ratio ranges are from about 400 to about 850 and from about 500 to about 700. In another embodiment of the invention, the aspect ratio of the short-cut, water non- dispersible polymer microfiber is about 300, about 400, about 500, about 600, about 700, and about 800.
• a short-cut microfiber- containing mixture comprising:
• water non-dispersible short-cut polymer microfibers having a fineness of 1 d/f or less; and wherein the water non-dispersible short- cut polymer microfiber has an aspect ratio of about 300 to about 1000;
• sulfopolyester dispersed in the water, wherein the sulfopolyester has a glass transition temperature (Tg) of at least 40°C,
• sulfopolyester comprises:
• n is an integer in the range of 2 to about 500;
• the instant invention also includes a fibrous article comprising the water-dispersible fiber, the multicomponent fiber, microdenier fibers, or water non-dispersible polymer microfibers described hereinabove.
• fibrous article is understood to mean any article having or resembling fibers.
• Non- limiting examples of fibrous articles include multifilament fibers, yarns, cords, tapes, fabrics, wet-laid webs, dry-laid webs, melt blown webs, spunbonded webs, thermobonded webs, hydroentangled webs, nonwoven webs and fabrics, and combinations thereof; items having one or more layers of fibers, such as, for example, multilayer nonwovens, laminates, and composites from such fibers, gauzes, bandages, diapers, training pants, tampons, surgical gowns and masks, feminine napkins; and the like.
• the water non-dispersible microdfibers can be utilized in filter media for air filtration, liquid filtration, filtration for food preparation, filtration for medical applications, and for paper making processes and paper products.
• the fibrous articles may include replacement inserts for various personal hygiene and cleaning products.
• the fibrous article of the present invention may be bonded, laminated, attached to, or used in conjunction with other materials which may or may not be water- dispersible.
• the fibrous article for example, a nonwoven fabric layer, may be bonded to a flexible plastic film or backing of a water non-dispersible material, such as polyethylene. Such an assembly, for example, could be used as one component of a disposable diaper.
• the fibrous article may result from overblowing fibers onto another substrate to form highly assorted combinations of engineered melt blown, spunbond, film, or membrane structures.
• the fibrous articles of the instant invention include nonwoven fabrics and webs.
• a nonwoven fabric is defined as a fabric made directly from fibrous webs without weaving or knitting operations.
• the Textile Institue defines nonwovens as textile structures made directly from fibre rather than yarn. These fabrics are normally made from continuous filments or from fibre webs or batts strengthened by bonding using various techniques, which include, but are not limited to, adhesive bonding, mechanical interlocking by needling or fluid jet entanglement, thermal bonding, and stitch bonding.
• the multicomponent fiber of the present invention may be formed into a fabric by any known fabric forming process.
• the resulting fabric or web may be converted into a microdenier fiber web by exerting sufficient force to cause the multicomponent fibers to split or by contacting the web with water to remove the sulfopolyester leaving the remaining microdenier fibers behind.
• Our invention thus provides a process for a microdenier fiber web, comprising:
• A spinning a water dispersible sulfopolyester having a glass transition temperature (Tg) of at least 57°C and one or more water non-dispersible polymers immiscible with the sulfopolyester into multicomponent fibers, the sulfopolyester comprising:
• n is an integer in the range of 2 to about 500; and (iv) 0 to about 20 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein the functional groups are hydroxyl, carboxyl, or a combination thereof.
• the multicomponent fibers have a plurality of segments comprising the water non-dispersible polymers wherein the segments are substantially isolated from each other by the sulfopolyester intervening between the segments; and the fiber contains less than 10 weight percent of a pigment or filler, based on the total weight of the fiber;
• a process for a microdenier fiber web which comprises:
• the multicomponent fibers have a plurality of domains comprising the water non-dispersible polymers wherein the domains are substantially isolated from each other by the sulfopolyester intervening between the domains; wherein the fiber has an as-spun denier of less than about 6 denier per filament; wherein the water dispersible sulfopolyester exhibits a melt viscosity of less than about 12,000 poise measured at 240°C at a strain rate of 1 rad/sec, and wherein the sulfopolyester comprising less than about 25 mole % of residues of at least one sulfomonomer, based on the total moles of diacid or diol residues;
• Step B collecting the multicomponent fibers of Step A) to form a non-woven web
• a process for a microdenier fiber web which comprises:
• Step (C) collecting the multicomponent fibers of Step (B) to form a non- woven web
• the process also preferably comprises prior to Step (C) the step of hydroentangling the multicomponent fibers of the non- woven web. It is also preferable that the hydroentangling step results in a loss of less than about 20 wt. % of the sulfopolyester contained in the multicomponent fibers, more preferably this loss is less than 15 wt. %, and most preferably is less than 10 wt. %.
• the water used during this process preferably has a temperature of less than about 45°C, more preferably less than about 35°C, and most preferably less than about 30°C.
• the water used during hydroentanglement be as close to room temperature as possible to minimize loss of sulfopolyester from the multicomponent fibers.
• removal of the sulfopolyester polymer during Step (C) is preferably carried out using water having a temperature of at least about 45 °C, more preferably at least about 60°C, and most preferably at least about 80°C.
• the non-woven web may under go a heat setting step comprising heating the non-woven web to a temperature of at least about 100°C, and more preferably at least about 120°C.
• the heat setting step relaxes out internal fiber stresses and aids in producing a dimensionally stable fabric product. It is preferred that when the heat set material is reheated to the temperature to which it was heated during the heat setting step that it exhibits surface area shrinkage of less than about 5% of its original surface area. More preferably, the shrinkage is less than about 2% of the original surface area, and most preferably the shrinkage is less than about 1%.
• the sulfopolyester used in the multicomponent fiber can be any of those described herein, however, it is preferable that the sulfopolyester have a melt viscosity of less than about 6000 poise measured at 240°C at a strain rate of 1 rad/sec and comprise less than about 12 mole %, based on the total repeating units, of residues of at least one sulfomonomer.
• melt viscosity less than about 6000 poise measured at 240°C at a strain rate of 1 rad/sec
• residues of at least one sulfomonomer are previously described herein.
• the inventive method preferably comprises the step of drawing the multicomponent fiber at a fiber velocity of at least 2000 m/min, more preferably at least about 3000 m/min, even more preferably at least about 4000 m/min, and most preferably at least about 5000 m/min.
• nonwoven articles comprising water non-dispersible polymer microfibers
• the nonwoven article comprises water non-dispersible polymer microfibers and is produced by a process selected from the group consisting of a dry-laid process and a wet-laid process. Multicomponent fibers and processes for producing water non- dispersible polymer microfibers were previously disclosed in the specification.
• At least 1% of the water non- dispersible polymer microfiber is contained in the nonwoven article.
• Other amounts of water non-dispersible polymer microfiber contained in the nonwoven article are at least 10%, at least 25%, and at least 50%.
• the nonwoven article can also further comprise at least one additive.
• Additives include, but are not limited to, starches, fillers, and binders. Other additives are discussed in other sections of this disclosure.
• manufacturing processes to produce these nonwoven articles from water non-dispersible microfibers produced from multicomponent fibers can be split into the following groups: dry-laid webs, wet-laid webs, and combinations of these processes with each other or other nonwoven processes.
• dry-laid nonwoven articles are made with staple fiber processing machinery which is designed to manipulate fibers in the dry state. These include mechnical processes, such as, carding, aerodynamic, and other air-laid routes. Also included in this category are nonwoven articles made from filaments in the form of tow, and fabrics composed of staple fibers and stitching filaments or yards i.e. stitchbonded nonwovens. Carding is the process of disentangling, cleaning, and intermixing fibers to make a web for further processing into a nonwoven article. The process predominantly aligns the fibers which are held together as a web by mechanical entanglement and fiber- fiber friction.
• Cards are generally configured with one or more main cylinders, roller or stationary tops, one or more doffers, or various combinations of these principal components.
• a card On example of a card is a roller card.
• the carding action is the combing or working of the water non-dispersible polymer microfibers between the points of the card on a series of interworking card rollers.
• Other types of cards include woolen, cotton, and random cards. Garnetts can also be used to align these fibers.
• the water non-dispersible polymer microfibers in the dried-laid process can also be aligned by air-laying. These fibers are directed by air current onto a collector which can be a flat conveyor or a drum.
• Extrusion-formed webs can also be produced from the multicomponents fibers of this invention. Examples include spunbonded and melt-blown. Extrusion technology is used to produce spunbond, meltblown, and porous-film nonwoven articles. These nonwoven articles are made with machinery associated with polymer extrusion methods such as melt spinning, film casting, and extrusion coating. The nonwoven article is then contacted with water to remove the water dispersible sulfopolyester thus producing a nonwoven article comprising water non-dispersible polymer microfibers.
• the water dispersible sulfopolyester and water non-dispersible polymer are transformed directly to fabric by extruding multicomponent filaments, orienting them as bundles or groupings, layering them on a conveying screen, and interlocking them.
• the interlocking can be conducted by thermal fusion, mechnical entanglement, hydroentangling, chemical binders, or combinations of these processes.
• water non-dispersible polymer microfibers are suspended in water, brought to a forming unit where the water is drained off through a forming screen, and the fibers are deposited on the screen wire.
• Step a the number of rinses depends on the particular use chosen for the water non-dispersible polymer microfibers.
• Step b) sufficient water is added to the microfibers to allow them to be routed to the wet-laid nonwoven zone.
• the wet-laid nonwoven zone comprises any equipment known in the art to produce wet-laid nonwoven articles.
• the wet-laid nonwoven zone comprises at least one screen, mesh, or sieve in order to remove the water from the water non-dispersible polymer microfiber slurry.
• the fibrous article may further comprise a water-dispersible film comprising a second water-dispersible polymer.
• the second water-dispersible polymer may be the same as or different from the previously described water- dispersible polymers used in the fibers and fibrous articles of the present invention.
• the second water-dispersible polymer may be an additional sulfopolyester which, in turn, comprises:
• the fibrous articles also may include various powders and particulates to improve absorbency or as delivery vehicles.
• our fibrous article comprises a powder comprising a third water-dispersible polymer that may be the same as or different from the water- dispersible polymer components described previously herein.
• powders and particulates include, but are not limited to, talc, starches, various water absorbent, water-dispersible, or water swellable polymers, such as poly(acrylonitiles), sulfopolyesters, and poly(vinyl alcohols), silica, pigments, and microcapsules.
• our nonwoven fabrics may be used as laminating adhesives or binders that may be bonded by known techniques, such as thermal, radio frequency (RF), microwave, and ultrasonic methods. Adaptation of sulfopolyesters to enable RF activation is disclosed in a number of recent patents.
• our novel nonwoven fabrics may have dual or even multifunctionality in addition to adhesive properties. For example, a disposable baby diaper could be obtained where a nonwoven of the present invention serves as both an water-responsive adhesive as well as a fluid managing component of the final assembly.
• n is an integer in the range of 2 to about 500; (iv) 0 to about 25 mole , based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein the functional groups are hydroxyl, carboxyl, or a combination thereof; wherein the polymer composition contains less than 10 weight percent of a pigment or filler, based on the total weight of the polymer composition; and (II) melt spinning filaments.
• a water-dispersible polymer optionally, may be blended with the sulfopolyester.
• the cation of the sulfonate salt may be a metal ion such as Li + , Na + , K + , Mg ++ , Ca ++ , Ni ++ , Fe ++ , and the like.
• the cation of the sulfonate salt may be non-metallic such as a nitrogenous base as described previously.
• sulfomonomer residues which may be used in the process of the present invention are the metal sulfonate salt of sulfophthalic acid, sulfoterephthalic acid, sulfoisophthalic acid, or combinations thereof.
• a circular piece (4" diameter) of the nonwoven produced in Example 2 was used as an adhesive layer between two sheets of cotton fabric.
• a Hannifin melt press was used to fuse the two sheets of cotton together by applying a pressure 35 psig at 200°C for 30 seconds.
• the resultant assembly exhibited exceptionally strong bond strength.
• the cotton substrate shredded before adhesive or bond failure. Similar results have also been obtained with other cellulosics and with PET polyester substrates. Strong bonds were also produced by ultrasonic bonding techniques.
• a PP (Exxon 3356G) with a 1200 MFR was melt blown using a 24" die to yield a flexible nonwoven fabric that did not block and was easily unwound from a roll. Small pieces (1" x 4") did not show any response (i.e., no disintegration or loss in basis weight) to water when immersed in water at RT or 50°C for 15 minutes.
• Unicomponent fibers of a sulfopolyester containing 82 mole isophthalic acid, 18 mole of sodiosulfoisophthalic acid, 54 mole diethylene glycol, and 46 mole 1,4-cyclohexanedimethanol with a Tg of 55°C were melt spun at melt temperatures of 245°C (473°F) on a lab staple spinning line. As- spun denier was approximately 8 d/f. Some blocking was encountered on the take-up tubes, but the 10-filament strand readily dissolved within 10 - 19 seconds in unagitated, demineralized water at 82°C and a pH between 5 and 6.
• Example 5 This prophetic example illustrates the possible application of the multicomponent and microdenier fibers of the present invention to the preparation of specialty papers.
• the blend described in Example 5 is co-spun with PET to yield bicomponent islands-in-the-sea fibers.
• the fiber contains approximately 35 wt% sulfopolyester "sea” component and approximately 65 wt% of PET "islands".
• the uncrimped fiber is cut to 1/8 inch lengths.
• these short-cut bicomponent fibers are added to the refining operation.
• the sulfopolyester "sea” is removed in the agitated, aqueous slurry thereby releasing the microdenier PET fibers into the mix.
• the microdenier PET fibers (“islands") are more effective to increase paper tensile strength than the addition of coarse PET fibers. Comparative Example 8
• Bicomponent fibers were made having a 108 islands in the sea structure on a spunbond line using a 24" wide bicomponent spinneret die from Hills Inc., Melbourne, FL, having a total of 2222 die holes in the die plate.
• Two extruders were connected to melt pumps which were in turn connected to the inlets for both components in the fiber spin die.
• the primary extruder (A) was connected to the inlet which metered a flow of Eastman F61HC PET polyester to form the island domains in the islands in the sea fiber cross-section structure.
• the extrusion zones were set to melt the PET entering the die at a temperature of 285°C.
• the secondary extruder (B) processed Eastman AQ 55S sulfopolyester polymer from Eastman Chemical Company, Kingsport, TN having an inherent viscosity of about 0.35 and a melt viscosity of about 15,000 poise, measured at 240°C and 1 rad/sec sheer rate and 9,700 poise measured at 240°C and 100 rad/sec sheer rate in a Rheometric Dynamic Analyzer RDAII (Rheometrics Inc. Piscataway, New Jersey) rheometer. Prior to performing a melt viscosity measurement, the sample was dried for two days in a vacuum oven at 60°C. The viscosity test was performed using a 25 mm diameter parallel-plate geometry at 1mm gap setting.
• the bicomponent fibers were laid down into a non- woven web having a fabric weight of 95 grams per square meter (gsm). Evaluation of the bicomponent fibers in this nonwoven web by optical microscopy showed that the PET was present as islands in the center of the fiber structure, but the PET islands around the outer periphery of the bicomponent fiber nearly coalesced together to form a nearly continuous ring of PET polymer around the circumference of the fibers which is not desireable. Microscopy found that the diameter of the bicomponent fibers in the nonwoven web was generally between 15-19 microns, corresponding to an average fiber as-spun denier of about 2.5 denier per filament (dpf). This represents a melt drawn fiber speed of about 2160 meters per minute.
• dpf denier per filament
• As-spun denier is defined as the denier of the fiber (weight in grams of 9000 meters length of fiber) obtained by the melt extrusion and melt drawing steps.
• the variation in bicomponent fiber diameter indicated non-uniformity in spun-drawing of the fibers.
• the non-woven web samples were conditioned in a forced-air oven for five minutes at 120°C.
• the heat treated web exhibited significant shrinkage with the area of the nonwoven web being decreased to only about 12% of the initial area of the web before heating.
• the bicomponent extrudates could not be melt drawn to the degree required to cause strain induced crystallization of the PET segments in the fibers.
• the AQ 55S sulfopolyester having this specific inherent viscosity and melt viscosity was not acceptable as the bicomponent extrudates could not be uniformly melt drawn to the desired fine denier.
• Example 9 Bicomponent extrudates having a 16- segment segmented pie structure were made using a bicomponent spinneret die from Hills Inc., Melbourne, FL, having a total of 2222 die holes in the 24 inch wide die plate on a spunbond equipment. Two extruders were used to melt and feed two polymers to this spinnerette die.
• the primary extruder (A) was connected to the inlet which fed Eastman F61HC PET polyester melt to form the domains or segment slices in the segmented pie cross-section structure.
• the extrusion zones were set to melt the PET entering the spinnerette die at a temperature of 285°C.
• the secondary extruder (B) melted and fed the sulfopolyester polymer of Example 8.
• the secondary extruder was set to extrude the sulfopolyester polymer at a melt temperature of 255°C into the spinnerette die. Except for the spinnerette die used and melt viscosity of the sulfopolyester polymer, the procedure employed in this example was the same as in Comparative Example 8. The melt throughput per hole was 0.6 gm/min. The volume ratio of PET to sulfopolyester in the bicomponent extrudates was set at 70/30 which represents a weight ratio of about 70/30.
• the bicomponent extrudates were melt drawn using the same aspirator used in Comparative Example 8 to produce the bicomponent fibers. Initially, the input air to the aspirator was set to 25 psi and the fibers had as-spun denier of about 2.0 with the bicomponent fibers exhibiting a uniform diameter profile of about 14-15 microns. The air to the aspirator was increased to a maximum available pressure of 45 psi without breaking the melt extrudates during melt drawing. Using 45 psi air, the bicomponent extrudates were melt drawn down to a fiber as-spun denier of about 1.2 with the bicomponent fibers exhibiting a diameter of 11-12 microns when viewed under a microscope.
• the speed during the melt draw process was calculated to be about 4500 m/min. Although not intending to be bound by theory, at melt draw rates approaching this speed, it is believed that strain induced crystallization of the PET during the melt drawing process begins to occur. As noted above, it is desirable to form some oriented crystallinity in the PET fiber segments during the fiber melt draw process so that the nonwoven web will be more dimensionally stable during subsequent processing.
• the bicomponent fibers using 45 psi aspirator air pressure were laid down into a nonwoven web with a weight of 140 grams per square meter (gsm).
• the shrinkage of the nonwoven web was measured by conditioning the material in a forced-air oven for five minutes at 120°C. This example represents a significant reduction in shrinkage compared to the fibers and fabric of Comparative Example 8.
• the sulfopolyester dissipated very readily into deionized water at a temperature of about 25°C. Removal of the sulfopolyester from the bicomponent fibers in the nonwoven web is indicated by the % weight loss. Extensive or complete removal of the sulfopolyester from the bicomponent fibers were observed at temperatures at or above 33°C. If hydroentanglement is used to produce a nonwoven web of these bicomponent fibers comprising the present sulfopolyester polymer of Example 8, it would be expected that the sulfopolyester polymer would be extensively or completely removed by the hydroentangling water jets if the water temperature was above ambient. If it is desired that very little sulfopolyester polymer be removed from these bicomponent fibers during the hydroentanglement step, low water temperature, less than about 25°C , should be used.
• a sulfopolyester polymer was prepared with the following diacid and diol composition: diacid composition (71 mol % terephthalic acid, 20 mol % isophthalic acid, and 9 mol % 5-(sodiosulfo) isophthalic acid) and diol composition (60 mol % ethylene glycol and 40 mol % diethylene glycol).
• the sulfopolyester was prepared by high temperature polyesterification under vacuum. The esterification conditions were controlled to produce a sulfopolyester having an inherent viscosity of about 0.31. The melt viscosity of this sulfopolyester was measured to be in the range of about 3000-4000 poise at 240°C and 1 rad/sec shear rate.
• the sulfopolyester polymer of Example 10 was spun into bicomponent segmented pie fibers and nonwoven web according to the same procedure described in Example 9.
• the primary extruder (A) fed Eastman F61HC PET polyester melt to form the larger segment slices in the segmented pie structure.
• the extrusion zones were set to melt the PET entering the spinnerette die at a temperature of 285°C.
• the secondary extruder (B) processed the sulfopolyester polymer of Example 10 which was fed at a melt temperature of 255°C into the spinnerette die.
• the melt throughput rate per hole was 0.6 gm/min.
• the volume ratio of PET to sulfopolyester in the bicomponent extrudates was set at 70/30 which represents the weight ratio of about 70/30.
• the cross-section of the bicomponent extrudates had wedge shaped domains of PET with sulfopolyester polymer separating these domains.
• the bicomponent extrudates were melt drawn using the same aspirator assembly used in Comparative Example 8 to produce the bicomponent fiber.
• the maximum available pressure of the air to the aspirator without breaking the bicomponent fibers during drawing was 45 psi.
• the bicomponent extrudates were melt drawn down to bicomponent fibers with as- spun denier of about 1.2 with the bicomponent fibers exhibiting a diameter of about 11-12 microns when viewed under a microscope.
• the speed during the melt drawing process was calculated to be about 4500 m/min.
• the bicomponent fibers were laid down into nonwoven webs having weights of 140 gsm and 110 gsm.
• the shrinkage of the webs was measured by conditioning the material in a forced-air oven for five minutes at 120°C.
• the area of the nonwoven webs after shrinkage was about 29% of the webs' starting areas.
• the sulfopolyester polymer dissipated very readily into deionized water at temperatures above about 46°C, with the removal of the sulfopolyester polymer from the fibers being very extensive or complete at temperatures above 51°C as shown by the weight loss.
• a weight loss of about 30% represented complete removal of the sulfopolyester from the bicomponent fibers in the nonwoven web. If hydroentanglement is used to process this non- woven web of bicomponent fibers comprising this sulfopolyester, it would be expected that the polymer would not be extensively removed by the hydroentangling water jets at water temperatures below 40°C.
• the nonwoven webs of Example 11 having basis weights of both 140 gsm and 110 gsm were hydroentangled using a hydroentangling apparatus manufactured by Fleissner, GmbH, Egelsbach, Germany.
• the machine had five total hydroentangling stations wherein three sets of jets contacted the top side of the nonwoven web and two sets of jets contacted the opposite side of the nonwoven web.
• the water jets comprised a series of fine orifices about 100 microns in diameter machined in two-feet wide jet strips.
• the water pressure to the jets was set at 60 bar (Jet Strip # 1), 190 bar (Jet Strips # 2 and 3), and 230 bar (Jet Strips # 4 and 5).
• the temperature of the water to the jets was found to be in the range of about 40- 45°C.
• the nonwoven fabric exiting the hydroentangling unit was strongly tied together.
• the continuous fibers were knotted together to produce a hydroentangled nonwoven fabric with high resistance to tearing when stretched in both directions.
• the hydroentangled nonwoven fabric after being heat set as described above, was washed in 90°C deionized water to remove the sulfopolyester polymer and leave the PET monocomponent fiber segments remaining in the hydroentangled fabric. After repeated washings, the dried fabric exhibited a weight loss of approximately 26 %. Washing the nonwoven web before hydroentangling demonstrated a weight loss of 31.3 %. Therefore, the hydroentangling process removed some of the sulfopolyester from the nonwoven web, but this amount was relatively small. In order to lessen the amount of sulfopolyester removed during hydroentanglement, the water temperature of the hydroentanglement jets should be lowered to below 40°C.
• the sulfopolyester of Example 10 was found to give segmented pie fibers having good segment distribution where the water non-dispersable polymer segments formed individual fibers of similar size and shape after removal of the sulfopolyester polymer.
• the rheology of the sulfopolyester was suitable to allow the bicomponent extrudates to be melt drawn at high rates to achieve fine denier bicomponent fibers with as-spun denier as low as about 1.0. These bicomponent fibers are capable of being laid down into a non- woven web which could be hydroentangled without experiencing significant loss of sulfopolyester polymer to produce the nonwoven fabric.
• the nonwoven fabric produced by hydroentangling the non-woven web exhibited high strength and could be heat set at temperatures of about 120°C or higher to produce nonwoven fabric with excellent dimensional stability.
• the sulfopolyester polymer was removed from the hydroentangled nonwoven fabric in a washing step. This resulted in a strong nonwoven fabric product with lighter fabric weight and much greater flexibility and softer hand.
• the monocomponent PET fibers in this nonwoven fabric product were wedge shaped and exhibited an average denier of about 0.1.
• a sulfopolyester polymer was prepared with the following diacid and diol composition: diacid composition (69 mol % terephthalic acid, 22.5 mol % isophthalic acid, and 8.5 mol % 5-(sodiosulfo) isophthalic acid) and diol composition (65 mol % ethylene glycol and 35 mol % diethylene glycol).
• the sulfopolyester was prepared by high temperature polyesterification under vacuum. The esterification conditions were controlled to produce a sulfopolyester having an inherent viscosity of about 0.33. The melt viscosity of this sulfopolyester was measured to be in the range of about 3000-4000 poise at 240°C and 1 rad/sec shear rate.
• the sulfopolyester polymer of Example 13 was spun into bicomponent islands-in-sea cross-section configuration with 16 islands on a spunbond line.
• the extrusion zones were set to melt the PET entering the spinnerette die at a temperature of about 290°C.
• the secondary extruder (B) processed the sulfopolyester polymer of Example 13 which was fed at a melt temperature of about 260°C into the spinnerette die.
• the volume ratio of PET to sulfopolyester in the bicomponent extrudates was set at 70/30 which represents the weight ratio of about 70/30.
• the melt throughput rate through the spinneret was 0.6 g/hole/minute.
• the cross-section of the bicomponent extrudates had round shaped island domains of PET with sulfopolyester polymer separating these domain
• the bicomponent extrudates were melt drawn using an aspirator assembly.
• the maximum available pressure of the air to the aspirator without breaking the bicomponent fibers during melt drawing was 50 psi.
• the bicomponent extrudates were melt drawn down to bicomponent fibers with as-spun denier of about 1.4 with the bicomponent fibers exhibiting a diameter of about 12 microns when viewed under a microscope.
• the speed during the drawing process was calculated to be about 3900 m/min.
• the sulfopolyester polymer of Example 13 was spun into bicomponent islands- in-the-sea cross-section fibers with 64 islands fibers using a bicomponent extrusion line.
• the primary extruder fed Eastman F61HC polyester melt to form the islands in the islands-in-the-sea fiber cross-section structure.
• the secondary extruder fed the sulfopolyester polymer melt to form the sea in the islands-in-sea bicomponent fiber.
• the inherent viscosity of polyester was 0.61 dL/g while the melt viscosity of dry sulfopolyester was about 7000 poise measured at 240°C and 1 rad/sec strain rate using the melt viscosity measurement procedure described earlier.
• These islands-in-sea bicomponent fibers were made using a spinneret with 198 holes and a throughput rate of 0.85 gms/minute/hole.
• the polymer ratio between "islands" polyester and “sea” sulfopolyester was 65% to 35%.
• These bicomponent fibers were spun using an extrusion temperature of 280°C for the polyester component and 260°C for the sulfopolyester component.
• the bicomponent fiber contains a multiplicity of filaments (198 filaments) and was melt spun at a speed of about 530 meters/minute, forming filaments with a nominal denier per filament of about 14.
• a finish solution of 24 wt% PT 769 finish from Goulston Technologies was applied to the bicomponent fiber using a kiss roll applicator.
• the filaments of the bicomponent fiber were then drawn in line using a set of two godet rolls, heated to 90°C and 130°C respectively, and the final draw roll operating at a speed of about 1750 meters/minute, to provide a filament draw ratio of about 3.3X forming the drawn islands-in-sea bicomponent filaments with a nominal denier per filament of about 4.5 or an average diameter of about 25 microns.
• These filaments comprised the polyester microfiber "islands" having an average diameter of about 2.5 microns.
• the drawn islands-in-sea bicomponent fibers of Example 15 were cut into short length fibers of 3.2 millimeters and 6.4 millimeters cut lengths, thereby, producing short length bicomponent fibers with 64 islands-in-sea cross-section configurations.
• These short cut bicomponent fibers comprised "islands" of polyester and "sea” of water dispersible sulfopolyester polymer.
• the cross- sectional distribution of islands and sea was essentially consistent along the length of these short cut bicomponent fibers.
• the drawn islands-in-sea bicomponent fibers of Example 15 were soaked in soft water for about 24 hours and then cut into short length fibers of 3.2 millimeters and 6.4 millimeters cut lengths.
• the water dispersible sulfopolyester was at least partially emulsified prior to cutting into short length fibers. Partial separation of islands from the sea component was therefore effected, thereby, producing partially emulsified short length islands-in-sea bicomponent fibers.
• Example 16 The short cut length islands-in-sea bicomponent fibers of Example 16 were washed using soft water at 80°C to remove the water dispersible sulfopolyester "sea" component, thereby, releasing the polyester microfibers which were the "islands" component of the bicomponent fibers.
• the washed polyester microfibers were rinsed using soft water at 25°C to essentially remove most of the "sea” component.
• the optical microscopic observation of the washed polyester microfibers showed an average diameter of about 2.5 microns and lengths of 3.2 and 6.4 millimeters.
• the short cut length partially emulsified islands-in-sea bicomponent fibers of Example 17 were washed using soft water at 80°C to remove the water dispersible sulfopolyester "sea" component, thereby, releasing the polyester microfibers which were the "islands" component of the fibers.
• the washed polyester microfibers were rinsed using soft water at 25°C to essentially remove most of the "sea” component.
• the optical microscopic observation of the washed polyester microfibers showed polyester microfibers of average diameter of about 2.5 microns and lengths of 3.2 and 6.4 millimeters.
• Wet-laid hand sheets were prepared using the following procedure. 7.5 gms of Albacel Southern Bleached Softwood Kraft (SBSK) from International Paper, Memphis, Tennessee, U.S.A. and 188 gms of room temperature water were placed in a 1000 ml pulper and pulped for 30 seconds at 7000 rpm to produce a pulped mixture. This pulped mixture was transferred into an 8 liter metal beaker along with 7312 gms of room temperature water to make about 0.1% consistency (7500 gms water and 7.5 gms fibrous material) pulp slurry. This pulp slurry was agitated using a high speed impeller mixer for 60 seconds. Procedure to make the hand sheet from this pulp slurry was as follows.
• the pulp slurry was poured into a 25 centimeters x 30 centimeters hand sheet mold while continuing to stir.
• the drop valve was pulled, and the pulp fibers were allowed to drain on a screen to form a hand sheet.
• 750 grams per square meter (gsm) blotter paper was placed on top of the formed hand sheet, and the blotter paper was flattened onto the hand sheet.
• the screen frame was raised and inverted onto a clean release paper and allowed to sit for 10 minutes.
• the screen was raised vertically away from the formed hand sheet.
• Two two sheets of 750 gsm blotter paper were placed on top of the formed hand sheet.
• the hand sheet was dried along with the three blotter papers using a Norwood Dryer at about 88°C for 15 minutes.
• One blotter paper was removed leaving one blotter paper on each side of the hand sheet.
• the hand sheet was dried using a Williams Dryer at 65 °C for 15 minutes.
• the hand sheet was then further dried for 12 to 24 hours using a 40 kg dry press.
• the blotter paper was removed to obtain the dry hand sheet sample.
• the hand sheet was trimmed to 21.6 centimeters by 27.9 centimeters dimensions for testing.
• Wet-laid hand sheets were prepared using the following procedure. 7.5 gms of Albacel Southern Bleached Softwood Kraft (SBSK) from International Paper, Memphis, Tennessee, U.S.A., 0.3 gms of Solivitose N pre-gelatinized quaternary cationic potato starch from Avebe, Foxhol, the Netherlands, and 188 gms of room temperature water were placed in a 1000 ml pulper and pulped for 30 seconds at 7000 rpm to produce a pulped mixture.
• SBSK Albacel Southern Bleached Softwood Kraft
• This pulped mixture was transferred into an 8 liter metal beaker along with 7312 gms of room temperature water to make about 0.1% consistency (7500 gms water and 7.5 gms fibrous material) to produce a pulp slurry.
• This pulp slurry was agitated using a high speed impeller mixer for 60 seconds. The rest of procedure for making hand sheet from this pulp slurry was same as in Example 20.
• Wet-laid hand sheets were prepared using the following procedure. 6.0 gms of Albacel Southern Bleached Softwood Kraft (SBSK) from International Paper, Memphis, Tennessee, U.S.A., 0.3 gms of Solivitose N pre-gelatinized quaternary cationic potato starch from Avebe, Foxhol, the Netherlands, 1.5 gms of 3.2 millimeter cut length islands-in-sea fibers of Example 16, and 188 gms of room temperature water were placed in a 1000 ml pulper and pulped for 30 seconds at 7000 rpm to produce a fiber mix slurry.
• SBSK Albacel Southern Bleached Softwood Kraft
• This fiber mix slurry was heated to 82°C for 10 seconds to emulsify and remove the water dispersible sulfopolyester component in the islands-in-sea fibers and release polyester microfibers.
• the fiber mix slurry was then strained to produce a sulfopolyester dispersion comprising the sulfopolyester and a microfiber-containing mixture comprising pulp fibers and polyester microfiber.
• the microfiber-containing mixture was further rinsed using 500 gms of room temperature water to further remove the water dispersible sulfopolyester from the microfiber-containing mixture.
• This microfiber-containing mixture was transferred into an 8 liter metal beaker along with 7312 gms of room temperature water to make about 0.1% consistency (7500 gms water and 7.5 gms fibrous material) to produce a microfiber-containing slurry.
• This microfiber-containing slurry was agitated using a high speed impeller mixer for 60 seconds. The rest of procedure for making hand sheet from this microfiber-containing slurry was same as in Example 20.
• Wet-laid hand sheets were prepared using the following procedure. 7.5 gms of MicroStrand 475-106 micro glass fiber available from Johns Manville, Denver, Colorado, U.S.A., 0.3 gms of Solivitose N pre-gelatinized quaternary cationic potato starch from Avebe, Foxhol, the Netherlands, and 188 gms of room temperature water were placed in a 1000 ml pulper and pulped for 30 seconds at 7000 rpm to produce a glass fiber mixture. This glass fiber mixture was transferred into an 8 liter metal beaker along with 7312 gms of room temperature water to make about 0.1% consistency (7500 gms water and 7.5 gms fibrous material) to produce a glass fiber slurry. This glass fiber slurry was agitated using a high speed impeller mixer for 60 seconds. The rest of procedure for making hand sheet from this glass fiber slurry was same as in Example 20.
• Wet-laid hand sheets were prepared using the following procedure. 3.8 gms of MicroStrand 475-106 micro glass fiber available from Johns Manville, Denver, Colorado, U.S.A., 3.8 gms of 3.2 millimeter cut length islands-in-sea fibers of Example 16, 0.3 gms of Solivitose N pre-gelatinized quaternary cationic potato starch from Avebe, Foxhol, the Netherlands, and 188 gms of room temperature water were placed in a 1000 ml pulper and pulped for 30 seconds at 7000 rpm to produce a fiber mix slurry.
• This fiber mix slurry was heated to 82°C for 10 seconds to emulsify and remove the water dispersible sulfopolyester component in the islands-in-sea bicomponent fibers and release polyester microfibers.
• the fiber mix slurry was then strained to produce a sulfopolyester dispersion comprising the sulfopolyester and a microfiber-containing mixture comprising glass microfibers and polyester microfiber.
• the microfiber-containing mixture was further rinsed using 500 gms of room temperature water to further remove the sulfopolyester from the microfiber-containing mixture.
• microfiber-containing mixture was transferred into an 8 liter metal beaker along with 7312 gms of room temperature water to make about 0.1% consistency (7500 gms water and 7.5 gms fibrous material) to produce a microfiber-containing slurry.
• This microfiber-containing slurry was agitated using a high speed impeller mixer for 60 seconds. The rest of procedure for making hand sheet from this microfiber-containing slurry was same as in Example 20.
• Example 25
• Wet-laid hand sheets were prepared using the following procedure. 7.5 gms of 3.2 millimeter cut length islands-in-sea fibers of Example 16, 0.3 gms of Solivitose N pre-gelatinized quaternary cationic potato starch from Avebe, Foxhol, the Netherlands, and 188 gms of room temperature water were placed in a 1000 ml pulper and pulped for 30 seconds at 7000 rpm to produce a fiber mix slurry. This fiber mix slurry was heated to 82°C for 10 seconds to emulsify and remove the water dispersible sulfopolyester component in the islands-in-sea fibers and release polyester microfibers.
• the fiber mix slurry was then strained to produce a sulfopolyester dispersion and polyester microfibers.
• the sulfopolyester dispersion was comprised of water dispersible sulfopolyester.
• the polyester microfibers were rinsed using 500 gms of room temperature water to further remove the sulfopolyester from the polyester microfibers.
• These polyester microfibers were transferred into an 8 liter metal beaker along with 7312 gms of room temperature water to make about 0.1% consistency (7500 gms water and 7.5 gms fibrous material) to produce a microfiber slurry.
• This microfiber slurry was agitated using a high speed impeller mixer for 60 seconds.
• the rest of procedure for making hand sheet from this microfiber slurry was same as in Example 20.
• the hand sheet samples of Examples 20-25 were tested and properties are provided in the following table.
• the hand sheet basis weight was determined by weighing the hand sheet and calculating weight in grams per square meter (gsm).
• Hand sheet thickness was measured using an Ono Sokki EG-233 thickness gauge and reported as thickness in millimeters. Density was calculated as weight in grams per cubic centimeter.
• Porosity was measured using a Greiner Porosity Manometer with 1.9 x 1.9 cm square opening head and 100 cc capacity. Porosity is reported as average time in seconds (4 replicates) for 100 cc of water to pass through the sample.
• Tensile properties were measured using an Instron Model TM for six 30 mm x 105 mm test strips. An average of six measurements is reported for each example. It can be observed from these test data that significant improvement in tensile properties of wet-laid fibrous structures is obtained by the addition of polyester microfibers of the current invention.
• the sulfopolyester polymer of Example 13 was spun into bicomponent islands-in-the- sea cross-section fibers with 37 islands fibers using a bicomponent extrusion line.
• the primary extruder fed Eastman F61HC polyester to form the "islands" in the islands-in-the-sea cross-section structure.
• the secondary extruder fed the water dispersible sulfopolyester polymer to form the "sea" in the islands-in-sea bicomponent fiber.
• the inherent viscosity of the polyester was 0.61 dL/g while the melt viscosity of dry sulfopolyester was about 7000 poise measured at 240°C and 1 rad/sec strain rate using the melt viscosity measurement procedure described previously.
• These islands-in-sea bicomponent fibers were made using a spinneret with 72 holes and a throughput rate of 1.15gms/minute/hole.
• the polymer ratio between "islands" polyester and “sea” sulfopolyester was 2 to 1.
• These bicomponent fibers were spun using an extrusion temperature of 280°C for the polyester component and 255°C for the water dispersible sulfopolyester component.
• This bicomponent fiber contained a multiplicity of filaments (198 filaments) and was melt spun at a speed of about 530 meters/minute forming filaments with a nominal denier per filament of 19.5.
• a finish solution of 24% by weight PT 769 finish from Goulston Technologies was applied to the bicomponent fiber using a kiss roll applicator.
• the filaments of the bicomponent fiber were then drawn in line using a set of two godet rolls, heated to 95°C and 130°C respectively, and the final draw roll operating at a speed of about 1750 meters/minute, to provide a filament draw ratio of about 3.3X forming the drawn islands-in-sea bicomponent filaments with a nominal denier per filament of about 5.9 or an average diameter of about 29 microns.
• These filaments comprised the polyester microfiber islands of average diameter of about 3.9 microns.
• the drawn islands-in-sea bicomponent fibers of Example 26 were cut into short length bicomponent fibers of 3.2 millimeters and 6.4 millimeters cut length, thereby, producing short length fibers with 37 islands-in-sea cross-section configurations.
• These fibers comprised "islands” of polyester and "sea” of water dispersible sulfopolyester polymers.
• the cross-sectional distribution of "islands” and "sea” was essentially consistent along the length of these bicomponent fibers.
• Example 27 The short cut length islands-in-sea fibers of Example 27 were washed using soft water at 80°C to remove the water dispersible sulfopolyester "sea” component, thereby, releasing the polyester microfibers which were the "islands” component of the bicomponent fibers.
• the washed polyester microfibers were rinsed using soft water at 25°C to essentially remove most of the "sea” component.
• the optical microscopic observation of the washed polyester microfibers had an average diameter of about 3.9 microns and lengths of 3.2 and 6.4 millimeters.
• the sulfopolyester polymer of Example 13 was spun into bicomponent islands-in-the- sea cross-section fibers with 37 islands fibers using a bicomponent extrusion line.
• the primary extruder fed polyester to form the "islands" in the islands-in-the-sea fiber cross-section structure.
• the secondary extruder fed the water dispersible sulfopolyester polymer to form the "sea" in the islands-in-sea bicomponent fiber.
• the inherent viscosity of the polyester was 0.52 dL/g while the melt viscosity of the dry water dispersible sulfopolyester was about 3500 poise measured at 240°C and 1 rad/sec strain rate using the melt viscosity measurement procedure described previously.
• These islands-in-sea bicomponent fibers were made using two spinnerets with 175 holes each and throughput rate of 1.0 gms/minute/hole.
• the polymer ratio between "islands" polyester and "sea” sulfopolyester was 70% to 30%.
• These bicomponent fibers were spun using an extrusion temperature of 280°C for the polyester component and 255°C for the sulfopolyester component.
• the bicomponent fibers contained a multiplicity of filaments (350 filaments) and were melt spun at a speed of about 1000 meters/minute using a take-up roll heated to 100°C forming filaments with a nominal denier per filament of about 9 and an average fiber diameter of about 36 microns.
• a finish solution of 24 wt% PT 769 finish was applied to the bicomponent fiber using a kiss roll applicator.
• the filaments of the bicomponent fiber were combined and were then drawn 3.
• Ox on a draw line at draw roll speed of 100 m/minute and temperature of 38°C forming drawn islands-in-sea bicomponent filaments with an average denier per filament of about 3 and average diameter of about 20 microns.
• These drawn island-in-sea bicomponent fibers were cut into short length fibers of about 6.4 millimeters length.
• These short length islands-in-sea bicomponent fibers were comprised of polyester microfiber "islands" of average diameter of about 2.8 microns.
• This fiber slurry was heated to 82°C for 10 seconds to emulsify and remove the water dispersible sulfopolyester component in the islands-in-sea bicomponent fibers and release polyester microfibers.
• the fiber slurry was then strained to produce a sulfopolyester dispersion and polyester microfibers.
• These polyester microfibers were rinsed using 500 gms of room temperature water to further remove the sulfopolyester from the polyester microfibers. Sufficient room temperature water was added to produce 352 ml of microfiber slurry.
• This microfiber slurry was re-pulped for 30 seconds at 7000 rpm. These microfibers were transferred into an 8 liter metal beaker.
• the remaining three quarters of the fiber slurry were similarly pulped, washed, rinsed and re-pulped and transferred to the 8 liter metal beaker. 6090 gms of room temperature water was then added to make about 0.49% consistency (7500 gms water and 36.6 gms of polyester microfibers) to produce a microfiber slurry. This microfiber slurry was agitated using a high speed impeller mixer for 60 seconds. The rest of procedure for making hand sheet from this microfiber slurry was same as in Example 20.
• the microfiber stock hand sheet with the basis weight of about 490 gsm was comprised of polyester microfibers of average diameter of about 2.5 microns and average length of about 3.2 millimeters.
• Wet-laid hand sheets were prepared using the following procedure. 7.5 gms of polyester microfiber stock hand sheet of Example 31, 0.3 gms of Solivitose N pre- gelatinized quaternary cationic potato starch from Avebe, Foxhol, the Netherlands, and 188 gms of room temperature water were placed in a 1000 ml pulper and pulped for 30 seconds at 7000 rpm. The microfibers were transferred into an 8 liter metal beaker along with 7312 gms of room temperature water to make about 0.1% consistency (7500 gms water and 7.5 gms fibrous material) to produce a microfiber slurry. This microfiber slurry was agitated using a high speed impeller mixer for 60 seconds. The rest of procedure for making hand sheet from this slurry was same as in Example 20. A 100 gsm wet-laid hand sheet of polyester microfibers was obtained having an average diameter of about 2.5 microns.
• the 6.4 millimeter cut length islands-in-sea bicomponent fibers of Example 29 were washed using soft water at 80°C to remove the water dispersible sulfopolyester "sea" component, thereby, releasing the polyester microfibers which were the "islands" component of the bicomponent fibers.
• the washed polyester microfibers were rinsed using soft water at 25°C to essentially remove most of the "sea” component.
• the optical microscopic observation of the washed polyester microfibers showed an average diameter of about 2.5 microns and lengths of 6.4 millimeters.
• Example 16 The short cut length islands-in-sea bicomponent fibers of Example 16, Example 27 and Example 29 were washed separately using soft water at 80°C containing about 1% by weight based on the weight of the bicomponent fibers of ethylene diamine tetra acetic acid tetra sodium salt (Na 4 EDTA) from Sigma-Aldrich Company, Atlanta, Georgia to remove the water dispersible sulfopolyester "sea" component, thereby, releasing the polyester microfibers which were the "islands" component of the bicomponent fibers.
• Na 4 EDTA ethylene diamine tetra acetic acid tetra sodium salt
• the washed polyester microfibers were rinsed using soft water at 25°C to essentially remove most of the "sea" component.
• the optical microscopic observation of washed polyester microfibers showed excellent release and separation of polyester microfibers.
• Use of a water softing agent, such as Na 4 EDTA in the water prevents any Ca ++ ion exchange on the sulfopolyester which can adversely affect the water dispersiblity of sulfopolyester.
• Typical soft water may contain up to 15 ppm of Ca ++ ion concentration. It is desirable that the soft water used in the processes described here should have essentially zero concentration of Ca ++ and other multi-valent ions or alternately use sufficient amount of water softening agent, such as Na 4 EDTA, to bind these Ca ++ ions and other multi-valent ions.
• water softening agent such as Na 4 EDTA
• the short cut length islands-in-sea bicomponent fibers of Example 16 and Example 27 were processed separately using the following procedure. 17 grams of Solivitose N pre- gelatinized quaternary cationic potato starch from Avebe, Foxhol, the Netherlands were added to the distilled water. After the starch was fully dissolved or hydrolyzed, then 429 grams of short cut length islands-in-sea bicomponent fibers were slowly added to the distilled water to produce a fiber slurry. A Williams Rotary Continuous Feed Refiner (5 inch diameter) was turned on to refine or mix the fiber slurry in order to provide sufficient shearing action for the water dispersible sulfopolyester to be separated from the polyester microfibers.
• the contents of the stock chest were poured into a 24 liter stainless steel container, and the lid was secured.
• the stainless steel container was placed on a propane cooker and heated until the fiber slurry began to boil at about 97 °C in order to remove the sulfopolyester component in the island-in-sea fibers and release polyester microfibers. After the fiber slurry reached boiling, it was agitated with a manual agitating paddle.
• the contents of the stainless steel container were poured into a 27 in x 15in x 6 in deep False Bottom Knuche with a 30 mesh screen to produce a sulfopolyester dispersion and polyester microfibers.
• the sulfopolyester dispersion comprised water and water dispersible sulfopolyester.
• the polyester microfibers were rinsed in the Knuche for 15 seconds with 10 liters of soft water at 17°C, and squeezed to remove excess water.
• polyester microfiber dry fiber basis
• Handsheets were made using the procedure described previously in Example 20.
• a sulfopolyester polymer was prepared with the following diacid and diol composition: diacid composition (69 mole percent terephthalic acid, 22.5 mole percent isophthalic 25 acid, and 8.5 mole percent 5-(sodiosulfo) isophthalic acid) and diol composition (65 mole percent ethylene glycol and 35 mole percent diethylene glycol).
• the sulfopolyester was prepared by high temperature polyesterification under a vacuum. The esterification conditions were controlled to produce a sulfopolyester having an inherent viscosity of about 0.33. The melt viscosity of this sulfopolyester was measured to be in the range of about 3,000 to 4,000 poise at 240°C and 1 rad/sec shear rate.
• the sulfopolyester polymer of Example 36 was spun into bicomponent islands-in-the-sea cross-section fibers with 37 islands using a bicomponent extrusion line.
• the primary extruder (A) fed Eastman F61HC PET polyester to form the "islands" in the islands-in-the-sea cross-section structure.
• the secondary extruder (B) fed the water dispersible sulfopolyester polymer to form the "sea" in the islands-in-sea bicomponent fiber.
• the inherent viscosity of the polyester was 0.61 dL/g while the melt viscosity of the dry sulfopolyester was about 7,000 poise measured at 240°C and 1 rad/sec strain rate using the melt viscosity measurement procedure described previously. These islands-in-sea bicomponent fibers were made using a spinneret with 72 holes. The polymer ratio between "islands" polyester and "sea" sulfopolyester was 2.33 to 1.
• bicomponent fibers were spun using an extrusion temperature of 280°C for the polyester component and 255°C for the water dispersible sulfopolyester component and subsequently drawn at a ratio of approximately 3.3: 1 to yield a final island diameter in the bicomponent fiber of approximately 2.5 micron.
• the sulfopolyester polymer of Example 36 was spun into bicomponent islands-in-the-sea cross-section fibers with 37 islands using a bicomponent extrusion line.
• the primary extruder (A) fed Eastman F61HC PET polyester to form the "islands" in the islands-in-the-sea cross-section structure.
• the secondary extruder (B) fed the water dispersible sulfopolyester polymer to form the "sea" in the islands-in-sea bicomponent fiber.
• the inherent viscosity of the polyester was 0.61 dL/g while the melt viscosity of the dry sulfopolyester was about 7,000 poise measured at 240°C and 1 rad/sec strain rate using the melt viscosity measurement procedure described previously. These islands-in-sea bicomponent fibers were made using a spinneret with 72 holes. The polymer ratio between "islands" polyester and "sea" sulfopolyester was 2.33 to 1.
• bicomponent fibers were spun using an extrusion temperature of 280°C for the polyester component and 255°C for the water dispersible sulfopolyester component and subsequently drawn at a ratio of approximately 3.3: 1 to yield a final island diameter in the bicomponent fiber of approximately 4.0 micron.
• the drawn islands-in-sea bicomponent fibers of Example 37 cut into short length bicomponent fibers of 1.5 mm (resulting in and island aspect ratio of 600) and the bicomponent fibers of Example 38 were cut into short length bicomponent fibers of 1.5 and 3.0 mm (resulting in an island aspect ratio of 375 and 750, respectively), thereby producing short length fibers with 37 islands-in-sea cross-section configurations.
• These fibers comprised "islands” of polyester and a "sea” of water dispersible sulfopolyester polymers.
• the cross-sectional distribution of "islands” and "sea” was essentially consistent along the length of these bicomponent fibers.
• the short cut length islands-in-sea fibers of Example 39 were independently washed using soft water at 80°C to remove the water dispersible sulfopolyester "sea” component, thereby releasing the polyester microfibers which were the "islands” component of the bicomponent fibers.
• the washed polyester microfibers were rinsed using soft water at 25°C to essentially remove most of the "sea" component.
• Wet-laid hand sheets comprising blends of the 600: 1 aspect ratio 2.5 micron diameter microfiber with the 750: 1 and 375: 1 aspect ratio 4.0 micron diameter microfibers collectively resulting from the "sea" component removal process of Example 40 were prepared using the following procedure: 2.0 grams of the polyester microfibers (dry fiber basis) were added to 2,000 ml of water and agitated using a modified blender for 1 to 2 minutes in order to make a microfiber slurry of 0.1 percent consistency. Procedure to make the hand sheet from this pulp slurry was as follows. The pulp slurry was poured into a 25 centimeters x 30 centimeters hand sheet mold while continuing to stir.
• the drop valve was pulled, and the pulp fibers were allowed to drain on a screen to form a hand sheet.
• 750 grams per square meter (gsm) blotter paper was placed on top of the formed hand sheet, and the blotter paper was flattened onto the hand sheet.
• the screen frame was raised and inverted onto a clean release paper and allowed to sit for 10 minutes.
• the screen was raised vertically away from the formed hand sheet.
• Two sheets of 750 gsm blotter paper were placed on top of the formed hand sheet.
• the hand sheet was dried along with the three blotter papers using a Norwood Dryer at about 88°C for 15 minutes. One blotter paper was removed leaving one blotter paper on each side of the hand sheet.
• the hand sheet was dried using a Williams Dryer at 65 °C for 15 minutes. The hand sheet was then further dried for 12 to 24 hours using a 40 kg dry press. The blotter paper was removed to obtain the dry hand sheet sample. The hand sheet was trimmed to 21.6 centimeters by 27.9 centimeters dimensions for testing. Characteristics of the hand sheets are detailed in Figures 1-3.
• Figures 1 and 2 indicate that the pore size and porosity of the resulting sheets increases predictably as the weight fraction of larger diameter fiber is increased. This increase is largely independent of the cut length (or aspect ratio) of the larger fiber.
• Figure 3 indicates that the lower aspect ratio 4.0 micron fiber (i.e. 1.5 micron length) significantly improves the formation (i.e the visual uniformity) of the synthetic hand sheet relative to its higher aspect ratio analog (i.e. 3.0 micron length).
• the 750: 1 aspect ratio (i.e. 3.0 mm) 4.0 micron fiber is blended with the 600: 1 aspect ratio (i.e.
• the uniformity of the hand sheet is observed to decrease slightly but significantly as the amount of 750: 1 aspect ratio 4.0 micron fiber is increased.
• the 375: 1 aspect ratio (i.e. 1.5 mm) 4.0 micron is blended with the 600: 1 aspect ratio (i.e. 1.5 mm) 2.5 micron fiber, a dramatic increase in the formation/uniformity of the hand sheet is observed.
• Figure 4 indicates that increasing the weight fraction of the larger diameter 4.0 micron fiber provides a more rapid increase in the average pore size of the sheet relative to the 2.5 micron fiber. It is worth noting, however, that very similar pore sizes are observed for the 50/50 blend of pulp and synthetic microfiber for both the 4.0 and 2.5 micron diameter synthetics.
• Figure 5 indicates a slight but significant improvement in uniformity/formation with increasing incorporation of the 600: 1 aspect ratio 2.5 micron diameter fiber but a dramatic increase in uniformity/formation with increasing incorporation of the 375: 1 aspect ratio 4.0 micron fiber.

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